Capacity of the WCDMA System Using High Altitude Platform Stations

In this paper, we provide a method to estimate the capacity of the wideband code division multiple access (WCDMA) scheme using High Altitude Platform Stations (HAPS), and demonstrate the results. This is to validate that the HAPS system is one of the most effective solutions to provide high quality wireless communication services, such as IMT-2000 services. We use a practical system model which describes the HAPS system most appropriately, and this leads to realistic estimation results. We estimate the reverse and forward link capacity of the HAPS WCDMA system and compare it to that of the terrestrial system. The estimation results show that the capacity of the HAPS WCDMA system is about 1.2–1.67 times larger than that of the terrestrial system.     

HAPS通信覆盖及链路特性分析

由高空平台(HAP)构成的信息系统将是新一代的无线通信系统,它融合了陆地和卫星通信系统的优势,又不同程度地避免了两者的缺点,在通信领域的应用得到了广泛认同,是现有通信方式的有效补充。通过重点研究高空平台站(HAPS)通信的覆盖特性、多波束小区划分方案、链路特性及功率控制等关键问题,提出了一种适应HAPS通信多波束小区划分方案,并且通过计算与仿真分析比较,说明提出方案更适应HAPS通信场景,为HAPS通信的工程实现提供了参考。     

The cellular phone industry in Malaysia: toward IMT-2000

Explosive growth of the cellular phone industry in Malaysia has been witnessed in the 1990s. Eight nationwide cellular phone operators with different technology bases exist in a single market. This article provides an overview of the telecommunications industry, especially the cellular phone sector, and also the activities on IMT-2000 in Malaysia     

高空平台不稳定性对HAPS通信性能影响建模与分析

 由于高空平台不可能静止驻留在空中,平台打转、摇摆等状态就会对HAPS(High Altitude Platform Stations)通信性能产生关键影响.目前的研究都处在假设平台稳定或调整波束指向能够补偿由于高空平台移动造成的剩余指向误差,存在很大的局限性,不能真实反应实际情况.本文通过建模把平台的不稳定性带来的影响反应到无线链路上,解决平台不稳定性等造成收发信号随机变化大而无法通信或通信质量差的问题.并通过仿真分析验证本文提出模型的正确性.     

High Altitude Platform Station (HAPS): A Review of New Infrastructure Development for Future Wireless Communications

This paper looks into the relatively new field of high altitude platform stations. HAPS is seen as a ‘middle ground’ between the terrestrial and satellite cases, and aims to exploit of the advantages of both types of system. Since HAPS is such a new field, this paper focuses on the technology behind a HAPS communications system, how this has developed, and compares it to the terrestrial and satellite equivalents. One important area that is being investigated is the applications for which HAPS should be used. This is a critical issue if a significant business case is to be made for HAPS. Worldwide HAPS projects and research issues are also highlighted. Finally, the review concludes with the remarks on the future of HAPS for wireless communications systems.     

高空通信平台的系统方案探讨

高空平台通信系统可与卫星和地面通信系统互补，是实现宽带无线通信的一种重要手段。本文简要介绍了分别采用飞艇和飞机作为载体的两种高空通信平台，并就高空平台通信系统的载体方案、工作频段和系统结构等方面提出了一些具体的设想。文中建议利用反向C频段开发我国的平流层通信系统，并就高空平台通信与卫星和地面微波通信在C频段的共存问题作了探讨。     

Satellite UMTS/IMT2000 W-CDMA air interfaces

The third-generation IMT-2000 initiative of the International Telecommunication Union is aiming at the provision of a limited family of global standards providing worldwide multimedia wireless services in a host of environments encompassing indoor picocells to satellite megacells. The ITU IMT-2000 initiative has been supported by several regional standardization bodies such as the European Telecommunication Standard Institute with its Universal Mobile Telecommunication System. In this article a few air interface proposals for the satellite component of UMTS/IMT-2000 based on adaptation of the emerging terrestrial wideband CDMA standards are reviewed. In particular, S-UMTS requirements are examined together with W-CDMA applicability to the satellite environment. It is shown that with minor adaptations, the terrestrial W-CDMA air interface provides an efficient solution for the satellite UMTS component. This commonality will certainly help in the realization of low-cost low-size dual-mode user terminals encompassing both terrestrial and satellite components     

TD-LTE-Advanced国际标准历程

2000年5月,中国提交的TD-SCDMA技术被国际电联接受为IMT-2000（3G）的国际标准;2010年10月,国际电联WP5D工作组确认中国提交的TD-LTE-Advanced技术成为IMT-Ad-vanced（4G）国际标准。从TD-SCDMA到TD-LTE-Advanced,10年时间里中国已经打造了比较完整地TD产业链,并在积极推动移动通信产业的发展。     

Small-scale fading for high-altitude platform (HAP) propagationchannels

There has been a great interest in the development of high-altitude platforms, which are low cost stratospheric aircraft carrying payloads tailored for a wide range of applications in telecommunications and remote sensing. These platforms are capable of flying at altitudes ranging between 17 and 30 km, with a potential endurance of weeks to months, features that make them attractive for the provision of future personal communication services. This paper deals with the theoretical derivation of a channel model for the communication link between the platform and terrestrial mobile users or stations. In particular, we address the problem of modeling the small-scale fading effects. It is shown that the particular geometry of the propagation scenario leads to a specific model applicable to the stratospheric channel     

Performance of CDMA/PRMA as an Access Technique for Integrated Services in a UMTS High Altitude Platform System

High Altitude Platforms (HAPs) have gained a great interest in recent years. HAP systems will be global in nature but national in service provision. They will deliver IMT-2000 mobile and fixed wireless access using the proposed IMT-2000 terrestrial component radio transmission technologies and protocols. Under the above consideration, in this paper the performance of a MAC protocol based on the combination of the well-known Packet Reservation Multiple Access (PRMA) scheme with Code Division Multiple Access (CDMA) technologies in a Frequency Division Duplex (FDD) mode is studied, for a HAP operating at the 2 GHz frequency band at an altitude of 22 km. The impact of acknowledgement delay has been examined through computer simulations, along with the selection of suitable channel access functions (CAFs) to control the access of mobile users. Moreover the protocol performance is investigated in a cellular HAP environment and compared to that of a ground-based system. Finally, different traffic scenarios have been considered in order to investigate the access delay for non-real time traffic and the packet dropping performance for real time traffic.Nikolaos Batsios received his diploma degree in electrical & computer engineering (Telecommunication Division) from Aristotle University of Thessaloniki (Greece) in 2000. At the end of his studies, his diploma thesis was awarded from ERICSSON Hellas. He was also one of the six finalists of the IEEE Region 8 Student Paper Contest. He has worked as a Research Engineer in Space Engineering S.p.A. (Rome, Italy) and he was involved in ATB, ROBMOD and VIRTUOUS projects. Currently he is working in Intracom S.A. as Telecom Engineer. His research interests are in the field of satellite and terrestrial communication systems including physical layer design, medium access control layer architectures and protocols.Fotini-Niovi Pavlidou received the PhD degree in electrical engineering from the Aristotle University of Thessaloniki, Greece, in 1988 and the diploma in mechanical-electrical engineering in 1979 from the same institution. She is currently an associate professor at the Department of Electrical and Computer Engineering at the Aristotle University engaged in teaching for the under- and post-graduate program in the areas of mobile communications and telecommunications networks. Her research interests are in the field of mobile and personal communications, satellite and HAP communications, multiple access systems, routing and traffic flow in networks and QoS studies for multimedia applications over the Internet. She is involved in many national and international projects in these areas and she has chaired the European COST262 Action on Spread Spectrum Techniques. She has served as a member of the TPC of many IEEE/IEE conferences. She is a permanent reviewer for many international journals. She has published about 80 papers in refereed journals and conferences. She is a senior member of IEEE, currently chairing the joint IEEE VTS & AESS Chapter in Greece.     

Harmonization of global third generation mobile systems

The International Telecommunication Union launched the third-generation project in 1986 with the aim to provide global personal communication using an inexpensive mobile terminal that can truly facilitate communication "anywhere, anytime". In previous years, standardization activities toward IMT-2000 have accelerated toward concrete specifications. By June 1998, a total of 15 proposals from around the world had been submitted to the ITU as radio transmission technology candidates. Since then, the 3G standardization landscape has seen many changes-a steady progression of the convergence process. This article provides a comprehensive overview of the worldwide harmonization efforts on the standardization of third-generation terrestrial mobile communication systems. The status, as of October 1999 when this article was written, of the technical specifications within 3G partnership projects are also summarized.     

An HTS 21-pole microstrip filter for IMT-2000 base stations with steep attenuation

We developed a 21-pole high-temperature superconductor thin-film microstrip filter with steep attenuation. This filter is applicable in the International Mobile Telecommunications-2000 (IMT-2000) base station receiver system, where high selectivity is needed to avoid interference from signals in the personal handyphone system (PHS) band just below the IMT-2000 band. The out-of-band rejection of this filter 1 MHz below the passband edge is more than 40 dB. Owing to the improvements of the design and the fabrication processes, we also eliminated the need for a tuning process in the fabrication processes in order to reduce the production costs and the turnaround time.     

Investigation of spurious emissions from cellular phones and the possible effect on aircraft navigation equipment

The study described in this paper investigated the possible interference of spurious emissions from cellular phones on aircraft navigation and communication equipment. Six wireless phone technologies were investigated over three frequency ranges, which covered the receiving ranges of five aircraft systems. The aircraft systems examined were very-high frequency omnidirectional range (VOR), localizer (LOC), very high frequency communication (VHF), glide slope (GS), and global positioning system (GPS). Research was performed in a semi-anechoic chamber (SAC) and a reverberation chamber (RC), with the phone at a distance of 1 m from the receiving antenna. Two antenna orientations were tested in the SAC. Initial tests yielded the appropriate height from the receiving antenna above the ground plane that would produce a maximum field measurement. Keypad programming was used to simulate worst-case phone transmissions. Radiated power measurements were performed and analyzed taking into consideration path loss results from the RTCA/DO-233 study. None of the six phone technologies investigated exhibited a power level greater than a 38-dBm path loss level above the maximum sensitivity of the aircraft system antennae when tested 1 m away from the antenna. These results indicate that, for the aircraft systems tested (VOR, LOC, VHF, GS, and GPS), the antenna of these systems would not have detected the emissions of the phones used in this study (CDMA-cellular, TDMA-11 Hz, TDMA-50 Hz cellular and PCS, GSM, and DCS-1800).     

Water Vapor Profiling From CoSSIR Radiometric Measurements

Previous water vapor profiling by millimeterwave radiometry using the 183-GHz absorption line is generally limited to an altitude range of 0-11 km. The additional measurements at the frequencies of 380.2 0.8, 380.2 1.8, 380.2 3.3, and 380.2 6.2 GHz by the new airborne compact scanning submillimeterwave imaging radiometer (CoSSIR) reported in this paper can extend this profiling capability up to an altitude of about 15 km. This is demonstrated by recent CoSSIR measurements onboard the NASA WB-57 aircraft in a flight from Texas to Costa Rica on January 14, 2006. Retrievals of water vapor mixing ratio were performed at eight altitudes of 1, 3, 5, 7, 9, 11, 13, and 15 km from the CoSSIR data set acquired at observational angles of 0 and 53.4. The results were compared with other available measurements from near-concurrent satellites. A very good agreement was found between the collocated values of total precipitable water (TPW) derived from the CoSSIR-retrieved water vapor profiles and those estimated from Tropical Rainfall Measuring Mission Microwave Imager; the average TPW differences range between 0.30 and 0.64 cm, depending on CoSSIR's observational angles. The accuracy of the retrievals was inferred from an analysis of inflight CoSSIR radiometric signal fluctuations.     

星地光通信中的精跟踪系统远场验证

 在星地光通信中,精跟踪系统的性能决定了整个APT系统的跟踪精度和带宽,是通信成败的关键因素。基于大容量图像数据实时处理和复杂控制,设计基于FPGA的并行处理精跟踪系统。跟踪控制算法采用自适应模糊－神经网络算法,可以实现系统参数在线实时动态调整。通过16Km的精跟踪系统演示实验,精跟踪系统抑制了平台振动和大气湍流对接收光功率的影响,有效提高了通信光束1550nm的光功率耦合效率,通过实验数据分析,精跟踪系统的跟踪精度达到了4.87μrad。     

Wide-band CDMA for the UMTS/IMT-2000 satellite component

This paper describes the main aspects relevant to the development of a third-generation radio transmission technology (RTT) concept identified as satellite wide-band CDMA (SW-CDMA), which has been accepted by the International Telecommunications Union (ITU) as one of the possible RTTs for the satellite component of International Mobile Telecommunications-2000 (IMT-2000). The main outcomes of the extensive system engineering effort that has led to the above ITU RTT are described. In particular, we address propagation channel characteristics, satellite diversity, power control, pilot channel, code acquisition, digital modulation and spreading format, interference mitigation, and resource allocation. Due to its similarity with respect to the terrestrial W-CDMA proposal from which it is derived, the SW-CDMA open air interface solution is described briefly, with emphasis only on the major adaptation required to best cope with the satellite environment. Quantitative results concerning the physical-layer performance over realistic channel conditions, for both forward and reverse link, are reported. A system capacity study case for a low-Earth-orbit constellation is also provided     

Pioneer Venus Orbiter Radar Mapper: Design And Operation

The Radar Mapper Experiment, carried abroad the Pioneer Venus Orbiter spacecraft, is designed to obtain a near-global picture of the topography, meter-scale surface slopes and reflectivity of Venus. Constraints imposed by the choice of orbit limit radar coverage to a latitude band lying between 74°N and 61°S completely around the planet. In addition to the altimetry objectives, the experiment seeks an image of the radar scattering properties of the surface at oblique incidence. Sensitivity limits the imaged region to a band around the planet lying between 45°N and 10°S. Altimetric error is less than 200 m; altimetric surface ?footprint? size varies from about 10 km in diameter at a spacecraft altitude of 200 km, to 50 km at a maximum altitude of 4700 km. Imaging resolution varies from 20 to 40 km, depending on spacecraft altitude.     

Automatic vehicle location in cellular communications systems

The paper presents a method of automatic vehicle location (AVL). Signals are transmitted from base stations in a cellular communications system. A device is embedded into a cellular phone installed in a vehicle. When this vehicle is traveling through a cellular territory, the device receives those signals and calculates the attenuation of those signals to locate the current vehicle position. A preliminary study by using computer simulation shows that the error between the exact position and the estimated position is in the range from 0 to 575 m. This result is based on the assumptions that the base stations are separated from each other by 5 km and the point-to-area terrain configuration has a 3 dB standard deviation of a normal signal strength distribution. A further modification by employing fuzzy logic is under development. The goal is to keep the location accuracy within 200 m     

TAWS低空风切变告警功能仿真验证平台设计

低空风切变对飞机运行安全会产生严重的威胁,而地形感知与告警系统(TAWS)的Mode 7能够根据飞机当前空速、攻角、无线电高度等探测低空风切变的存在,从而提示飞行员躲避危险,避免可控飞行撞地(CFIT)的发生以确保飞行安全。为了解决TAWS Mode 7功能验证时难以建立真实装机试飞环境的问题,针对某航空研究所研制的TAWS工程样机,设计了低空风切变探测功能的仿真验证平台。仿真验证平台以低空风切变模型和六自由度飞机模型为核心生成低空风切变探测所需的数据,利用飞行场景数据库进行多次仿真,可以验证TAWS Mode 7是否能在飞机穿越风切变时给出准确的提示和告警信息。